In industrial sensor applications, e.g., for detecting temperature or pressure, the power supply needs to be isolated from the analog front end for safety and equipment protection. The power interface mandates resilience to Common Mode Transients that can be higher than 100 KV/μs, so high-voltage isolation devices, e.g., transformers/capacitors, are necessary. In this setting, efficiency is difficult to maintain above 50% at output power ranges below 50 mW, especially when large parasitic resistance and capacitance exist on high-voltage devices. Additionally, the form factor, e.g., less than about 3×3 mm2 and in some cases, less than about 2 mm wide, is critical to sensor applications such as field transmitters. However, the use of high-voltage transformers usually incurs a large area cost.
Today, most, if not all, existing choices in the isolation power market are based on transformers. Because of the large amounts of space necessary for transformer implementation, these existing choices cannot meet the above requirements for size, with several isolation power devices having dimensions ranging from 7×7 mm2 to 15×15 mm2. Additionally, the existing choices are not power-efficient in the low-power region, with efficiencies ranging from 10-40% at 25 mW.